Environmental predictors for annual fish assemblages in subtropical grasslands of South America: the role of landscape and habitat characteristics

Annual fishes (AF) are ecologically unique assemblage with major conservation concern. Several AF species are found in temporary waters of South American subtropical grasslands, an ecoregion largely neglected by conservation policies. We applied a broad-scale approach to understand distribution pattern of the AF and tested the effects of environmental predictors on occurrence, abundance and assemblage structure of this diverse Neotropical group of threatened endemic aquatic fauna. We recorded 23 AF species. AF assemblage was strongly spatially structured and many individual species formed discrete units. AF presence was negatively associated with altitude at the landscape scale, and negatively associated with maximum pool depth and presence of predatory fish at the local scale. We found negative association between AF abundance and water depth. Assemblage composition was spatially structured, differed among hydrographic regions and was influenced by altitude, temperature and monthly precipitation. AF inhabits highly vulnerable habitats currently located in livestock and agricultural landscapes. Habitat maintenance through wildlife-friendly practices should be considered as an alternative to promote AF conservation.     

In vivo knockdown of antisense non‐coding mitochondrial RNAs by a lentiviral‐encoded shRNA inhibits melanoma tumor growth and lung colonization

The family of non‐coding mitochondrial RNAs (ncmtRNA) is differentially expressed according to proliferative status. Normal proliferating cells express sense (SncmtRNA) and antisense ncmtRNAs (ASncmtRNAs), whereas tumor cells express SncmtRNA and downregulate ASncmtRNAs. Knockdown of ASncmtRNAs with oligonucleotides induces apoptotic cell death of tumor cells, leaving normal cells unaffected, suggesting a potential application for developing a novel cancer therapy. In this study, we knocked down the ASncmtRNAs in melanoma cell lines with a lentiviral‐encoded shRNA approach. Transduction with lentiviral constructs targeted to the ASncmtRNAs induced apoptosis in murine B16F10 and human A375 melanoma cells in vitro and significantly retarded B16F10 primary tumor growth in vivo. Moreover, the treatment drastically reduced the number of lung metastatic foci in a tail vein injection assay, compared to controls. These results provide additional proof of concept to the knockdown of ncmtRNAs for cancer therapy and validate lentiviral–shRNA vectors for gene therapy.     

When phylogeny and ecology meet: Modeling the occurrence of Trichoptera with environmental and phylogenetic data

Ecological studies are increasingly considering phylogenetic relationships among species. The phylogeny is used as a proxy or filter to improve statistical tests and retain evolutionary elements, such as niche conservation. We used the phylogenetic topology to improve the model for occurrence of Trichoptera genera in Cerrado (Brazilian Savanna) streams. We tested whether parameters generated by logistic models of occurrence, using phylogenetic signals, are better than models generated without phylogenetic information. We used a model with Bayesian updating to examine the influence of stream water pH and phylogenetic relationship among genera on the occurrence of Trichoptera genera. Then, we compared this model with the logistic model for each Trichoptera genus. The probability of occurrence of most genera increased with water pH, and the phylogeny‐based explicit logistic model improved the parameters estimated for observed genera. The inferred relationship between genera occurrence and stream pH improved, indicating that phylogeny adds relevant information when estimating ecological responses of organisms. Water with elevated acidity (low pH values) may be restrictive for the occurrence of Trichoptera larvae, especially if the regional streams exhibit neutral to alkaline water, as is observed in the Cerrado region. Using phylogeny‐based modeling to predict species occurrence is a prominent opportunity to extend our current statistical framework based on environmental conditions, as it enables a more precise estimation of ecological parameters.     

Reaction heat measurements in the enzymatic hydrolysis reaction of penicillin GK to obtain 6-APA

The purpose of this study was to measure heats involved in the hydrolysis process for the industrial production of 6-aminopenicillanic acid (6-APA) using dynamic calorimetry techniques. The experimental design was planned using Hess' law. The information derived from the calorimeter was correlated mathematically to determine the heat released during enzymatic hydrolysis. This is important for temperature control systems and reactor design. The results obtained with the calorimetric measurements at 308 K and pH 7.5 are the penicillin hydrolysis, ΔH_hydrol, at 35.9 ± 5.7 kJ mol⁻¹ and phenyl acetic acid neutralization, ΔH_neut, at −47.1 ± 3.8 kJ mol⁻¹.     

A requirement for an unconjugated pteridine for the growth of Paramecium aurelia

The ciliated protozoan Paramecium aurelia requires exceptionally high levels (microgram amounts) of folic acid for optimal growth when cultured in a compex synthetic medium. This requirement may be replaced by nanogram quantities of the vitamin provided the unconjugated pteridine biopterin is present in the medium. Both folic acid and biopterin are essential for optimal growth. Evidence has been obtained that the growth-promoting effect of abnormally high concentrations of folic acid may be due to the ability of the protozoan to convert small quantities of the vitamin into biopterin or other nutritionally active pteridines.